import java.util.Scanner;

public class Test {

    /*
     *  业务逻辑
     * */
    static char getGradeByIf(float score) {
        char grade;
        if (score >= 90) {
            grade = 'A';
        } else if (score >= 80) {
            grade = 'B';
        } else if (score >= 70) {
            grade = 'C';
        } else if (score >= 60) {
            grade = 'D';
        } else {
            grade = 'F';
        }
        return grade;
    }

    /*
     *  业务逻辑
     * */
    static char getGradeBySwitch(float score) {
        char grade = 'F';
        int r = (int)(score / 10);
//        int result =  Math.floor(r);

        switch (r) {
            case 10:
            case 9:
                grade = 'A';
                break;
            case 8:
                grade = 'B';
                break;
            case 7:
                grade = 'C';
                break;
            case 6:
                grade = 'D';
                break;
            default:
                grade = 'F';
                break;
        }
        return grade;
    }


    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        float score;
        char grade;

        // 界面逻辑
        score = input.nextFloat();

//        grade = getGradeByIf(score);

        grade = getGradeBySwitch(score);

        // 界面逻辑
        System.out.printf("分数为：%.1f,等级为：%c\n", score, grade);
    }
}
